Drilling bit



Nov. 3, 1942. w, Ew 2,300,805

, DRILLING BIT Filed Jan. 15, 1941 2 Sheets-Sheet l :lVUi/YM THonAs.W. PEw

Nov. 3, 1942.

T. w. PEW 2,300,805

DRILLING BIT Filed Jan. 13, 1941 2 Sheets-Sheet 2 THOMAS W. FEW.

INVENTOR.

Jun (5.

Patented Nov. 3, 1942 FICE'.

DRILLING BIT Thomas W. Pew, Houston, Tex.

Application January 13, 1941, Serial No. 374,273

1 Claim.

The invention relates to a drilling or drag bit of the type used in drilling wells by the rotary method. .1

In drilling wells by the rotary method wher the drilling mud or slush is forced downwardly through the drill stem to discharge through the bit or circulate upwardly in the well bore it is desirable that the cuttings be carried away from the cutting blade as quickly as possible to avoid the cuttings being ground .up between the bit and the wall of the well bore.

With many types of bits the cuttings are churned about in the bore by the bit before they rise to such an elevation that they no longer interfere with the cutting edge of the bit or with the gauge maintaining face. The present invention has therefore been devised with a view'of providing a bit which will have an exceptionally large clearance for the circulating liquid so as to facilitate the circulation away from the cutting edge of the cuttings or chips from the bit.

It is one of the objects of the invention to proa well bore to illustrate the large circulation area for the escape of cuttings.

Fig. 6 is a Fig. 5.

Fig. 7 is a transverse sectional view of an eccentric type of bit used for straight hole work.

In Fig.1 the bit body is illustrated generally at 2 and is made up of a roundor cylindrical portion which has been formed with a box 3 at its upper end. This box is arranged to receive the pin down on the drill stem or drill collar 35 by'which the bit is rotated and manipulated in the well bore.

The shank 5 forms the lower portion of the bit and the tapered area 6 merges the shank 5 with the body 2 because, as is seen in Fig. 2, the shank section taken on the line 6-5 of 5 is of substantially lesser diameter than the vide a drag bit which will allow the escape of the cuttings without causing the cuttings to be recut.

Another object of the invention is to provide a drag bit which will avoid balling up of the bit due to the fact that gumbo or sticky shale and cuttings adhere to the cutting blade.

Another object of the invention is to provide a drag bit which will remain sharp for a longer period and will maintain a full gauge hole for a longer period because the cuttings are permitted to escape from the bit.

Another object of the invention is to provide a bit having a body or shank and cutting blades attached to the shank by reinforced or wing portions of reduced size to permit the escape of the cuttings.

Other and further objects of the invention will be readily apparent when the following description is considered in connection with the accompanying drawings wherein:

Fig. l is a side elevation of a drag bit of the three-way type to which the invention has been applied.

Fig. 2 is a vertical transverse section through the bit of Fig. 1. v v

Fig. 3 is a bottom plan view looking up at the cutting edge of the blade.

Fig. 4 is a transverse section of an eccentric type of bit embodying the invention which will be used for straight hole work.

body 2.

'l'ne shank 5 is curved at 1 arh'acent the base 8 thereof and has an enlarged cavity 9 therein which is joined by the water course It leading from the box portion 3.

This water course is provided to discharge the drilling mud from the bit, and an apron I2 is formed on the shank so as to provide a space for the discharge nipple [3 which forms the port [4 for discharging the drilling liquid. This nipple is inclined so that the fluid discharging therefrom will act as a'hydraulic jet to help advance the bit.

The cutter blades [6 for the bit may be arranged in any desired position and maybe either two, three or four in number, depending upon the type of bit to be constructed. These blades are either formed integrally with the shank 5,

or welded or removably attached as desired. Each blade has the lower cutting edge 20 which is arranged to drag on the bottom 2| of the well bore or hole 22, as seen in Fig. 5. Each of the blades has a side or edge face 24 which is known as the gauge cutting face because it is this face that cuts the side wall of the hole and maintains it at the desired diameter.

In drag bits of this type the body 2 extends down to join the top of the blade so that the cuttings and return flow are crowded into a small space around the body. In the present bit, however, it should be noted that the body has been cut away except for the reinforcing wings 26. The curved surface 25 merges the top edge of the blade IS with these reinforcing ribs or wing portions 26 which project radially from the shank 5 but are preferably of a diameter substantially equal to or slightly less thanthe diameter of the Fig. 5 is a side elevation of the bit positioned in body 2. This structure is provided, as seen in Fig. 5, for insuring as large a passage 30 as possible along the shank 5 of the bit.

It should be particularly noted that the cuttings leaving the cutting ed e 20 on the bottom 2| of the hole need travel upwardly only an elevation equal to the length of the gauge cutting face 24 in order to be free of the bit. When the cuttings reach the elevation above the edge 25 they mingle with the other cuttings from the other blades and move upwardly with the circulation.

This feature is of material advantage because the cuttings are not caused to be recut by the gauge cutting face 24. In actual practice it has been found that the cuttings or chips emerge at the surface of the well with the circulating liquid in much larger pieces or chips with the present type of bit than do the chips from the ordinary and usual types of drag bits. This is a positive indication that the chips are being carried away from the cutting blade before they are milled up by the blade in the well bore or reground or recut by the bit.

Another point of advantage with the present bit is that, in view of the fact that the clearance is increased and thatthe cuttings are able to move away from the cutting blade, the bit does not become balled up by having the cuttings adhere to the cutting blades. In many types of gumbo or sticky shale considerable delay is encountered in the drilling operation due to the fact that the bit balls up when the material sticks to the cutting blades or the body of the bit. With the present bit less material adheres to the blades and body because there is an increased clearance for the circulation of the cuttings away from the blades and it has been impossible in practice to ball up the hit. As a result of these advantages the bit stays sharp for a longer period of time and it is possible to cut a full gauge hole for a longer distance because the wear on the blade portions, both bottom and sides, occurs only by making the original cut on the formation and not in recutting or milling up the material which has been previously cut.

Figs. 4 and 7 show the same type of construction where the box member 3 is positioned eccentrically of the body. This causes one of the cutting blades, such as 40, to extend eccentrically a greater distance from the center of rotation than it does in the concentric type of constructionofFigs.lor5. Abiofthistypelsusedin' correcting the inclination of the well bore where the weight of the drill stem or drill collar 35 must be raised from the low side of the hole due to the eccentricity of the bit itself. This insures a heavier cut on the lower side of the hole so that there is a gradual tendency to straighten up the hole.

In Fig. 3 one of the blades I 6 has been extended very slightly at 4|, say, for purposes of illustration, about one-eighth of an inch. This structure will initiate a slight sliding movement of the cutting edges of the bit on the bottom of the bore which has been found to increase the speed of cutting possibly because of the slight shaving action thus created.

Broadly, the invention contemplates a drag bit wherein a maximum clearance for the escape of the cuttings is provided.

What is claimed is:

A drag bit including a body, a box member to receive the drill stem or drill collar, a shank on said body of .smaller diameter than said body and projecting below the body, a tapered area merging the body and shank, a water course through said body and shank, a discharge port in the base of the shank including an apron over the port, said shank having a bulb portion at its base, a plurality of cutter blades projecting below said shank and radially thereof, each blade having a gauge face at itsouter edge of alength to extend above the base of the shank and abcve said port, and a wing portion disposed along the shank and said tapered area to merge with the body whereby a circulation passage along the shank is provided in front of each blade and the circulation from said passage allowed to mingle in the bore about the body.

THOMAS W. PEW. 

